/*-------------------------------------------------------------------------
 *
 * nodeFuncs.c--
 *    All node routines more complicated than simple access/modification
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /usr/local/cvsroot/postgres95/src/backend/nodes/nodeFuncs.c,v 1.2 1996/10/31 10:42:56 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */

#include <sys/types.h> 

#include "postgres.h"

#include "nodes/primnodes.h"
#include "nodes/plannodes.h"
#include "nodes/pg_list.h"
#include "nodes/relation.h"
#include "nodes/nodeFuncs.h"
#include "utils/lsyscache.h"

/*    
 * single_node -
 *    Returns t if node corresponds to a single-noded expression
 */
bool
single_node(Node *node)
{
    if(IsA(node,Ident) || IsA(node,Const) || IsA(node,Var) || IsA(node,Param)) 
	return(true);
    else
	return(false);
}

/*****************************************************************************
 *    	VAR nodes
 *****************************************************************************/

/*    
 *    	var_is_outer
 *    	var_is_inner
 *    	var_is_mat
 *    	var_is_rel
 *    
 *    	Returns t iff the var node corresponds to (respectively):
 *    	the outer relation in a join
 *    	the inner relation of a join
 *    	a materialized relation
 *    	a base relation (i.e., not an attribute reference, a variable from
 *    		some lower join level, or a sort result)
 *      var node is an array reference
 *    
 */
bool
var_is_outer (Var *var)
{
    return((bool)(var->varno == OUTER));
}

bool
var_is_inner (Var *var)
{
    return ( (bool) (var->varno == INNER));
}

bool
var_is_rel (Var *var)
{
    return (bool)
	! (var_is_inner (var) ||  var_is_outer (var));
}

/*****************************************************************************
 *    	OPER nodes
 *****************************************************************************/

/*    
 * replace_opid -
 *    
 *    	Given a oper node, resets the opfid field with the
 *    	procedure OID (regproc id).
 *    
 *    	Returns the modified oper node.
 *    
 */
Oper *
replace_opid (Oper *oper)
{
    oper->opid = get_opcode(oper->opno);
    oper->op_fcache = NULL;
    return(oper);
}

/*****************************************************************************
 *    	constant (CONST, PARAM) nodes
 *****************************************************************************/

/*    
 * non_null -
 *    	Returns t if the node is a non-null constant, e.g., if the node has a
 *    	valid `constvalue' field.
 *    
 */
bool
non_null (Expr *c)
{
    
    if ( IsA(c,Const) && ! ((Const*)c)->constisnull )
	return(true);
    else
	return(false);
}



